In ink jet recording greatly spread in market in recent years in particular, many technical approaches and proposals have been disclosed in recording media for the purpose of achieving coloring ability and image fastness equivalent or superior to those of a silver halide photograph. Among these, there have been lots of proposals for causing a metal ion or metal salt to coexist in an ink-receiving layer in addition to ink-receiving materials for the purpose of improving the fastness properties of the resulting recorded image.
For example, proposals of a recording medium obtained by overcoating an ink-receiving layer with a liquid medium containing a metal ion or metal salt dissolved therein include the following proposals. Japanese Patent Application Laid-Open No. S55-053591 discloses recording paper obtained by post-coating a recording surface of a recording medium with an aqueous solution of a water-soluble metal salt for the purpose of improving the water resistance of the resulting recorded image. Japanese Patent Application Laid-Open No. S55-150396 discloses recording paper obtained by post-coating the recording surface of a recording medium with a water-proofing agent which forms lake with a dye. Japanese Patent Application Laid-Open No. S59-096988 discloses a recording medium obtained by post-coating a pigment-containing ink-receiving layer of the recording medium with a water-soluble salt compound of a metal having an ionic valency of 2 or higher as an improver for the ink-receiving layer for the purpose of improving the water resistance of the resulting recorded image. Japanese Patent Application Laid-Open No. H04-323075 discloses a recording sheet obtained by post-coating an alumina hydrate-containing layer of a recording medium having the alumina hydrate-containing layer with a divalent metal ion solution for the purpose of improving the color reproducibility of the resulting recorded image and achieving a high color density. Japanese Patent Application Laid-Open No. H08-112969 discloses an ink jet recording medium obtained by post-coating an alumina hydrate-containing ink-receiving layer of a recording medium having the ink-receiving layer with a solution of a transition metal salt forming a complex with a dye molecule for the purpose of inhibiting bleed or migration of the resulting recorded image. Japanese unexamined Patent Publication No. 2003-514699 discloses an ink jet recording medium obtained by post-coating a silica-containing ink-receiving layer of a recording medium with a solution of an organic metal polyvalent metal salt for the purpose of improving the quality and washing resistance of the resulting recorded image.
Recording media using an ink-receiving layer obtained by coating a substrate with a coating liquid containing both inorganic pigment dispersed therein and metal salt compound dissolved therein have also been proposed. Japanese Patent Application Laid-Open No. S58-094491 discloses an ink jet recording sheet containing synthetic silica and a weak acid salt or oxide compound of a divalent metal for the purpose of improving the discoloration/fading resistance of a coloring material. Japanese Patent Application Laid-Open No. H10-329404 discloses an ink jet recording medium containing in an ink-receiving layer a mixture of a porous aluminum oxide usable as a carrier for catalysts and ceramics and a compound having an element of a rare earth metal series and having an atomic number of from 57 to 71 in a periodic system. Japanese Patent Application Laid-Open No. S61-043593 discloses an ink jet recording medium coated with a coating liquid containing a porous inorganic pigment and magnesium sulfate and/or a complex salt thereof. Japanese Patent Application Laid-Open No. S61-057380 discloses an ink jet recording medium containing a porous inorganic pigment and hardly soluble magnesium. Japanese Patent Application Laid-Open No. S61-057379 discloses an ink jet recording medium containing a porous inorganic pigment and a water-soluble aluminum salt. Japanese Patent Application Laid-Open No. S61-063477 discloses an ink jet recording medium obtained by causing both porous inorganic pigment and hardly soluble magnesium compound such as magnesium oxide or magnesium carbonate to be contained in an ink-receiving layer for the purpose of improving light resistance, water resistance and color density.
Inorganic pigments subjected to a specific cationization treatment and ink jet recording media using such an inorganic pigment have also been known. Specifically, Japanese Patent Application Laid-Open No. S63-166586 discloses a recording medium containing silica surface-treated with a metal soap, hydroxide, salt or oxide of a metal for the purpose of improving water resistance and light resistance. This publication only discloses, regarding a method for surface-treating silica, aging for 20 minutes under heating conditions of 90° C. upon synthesis of silica as well as the timing of adding the metal compound for the surface treatment. Japanese Patent Application Laid-Open No. H03-218887 discloses an ink jet recording medium containing a magnesium-containing inorganic pigment surface-treated with an aluminum compound or silicon compound at a heating temperature of 90° C. for the purpose of improving the storage stability of the resulting recorded image. Japanese Patent Application Laid-Open No. H01-258980 discloses a recording medium using an organic cationic polymer having a silane-coupling site or a pigment having a surface of subjected to a cationization treatment with a metal oxide for the purpose of improving the storage stability of the resulting recorded image. Japanese Patent Application Laid-Open No. H01-259982 discloses an ink jet recording sheet using silica surface-treated with calcium, magnesium or barium by heating for 20 minutes at 90° C. for the purpose of improving light resistance.
Japanese Patent Application Laid-Open No. H06-220251 discloses a method for forming a reactive metal site on the surface of a particle property modifier by subjecting the surface of the modifier to a metal ion activating treatment. Japanese Unexamined Patent Publication No. 2004-504136 discloses a method for modifying a catalyst carrier by chemically bonding a hydroxyl group of an untreated catalyst carrier partially dissolved in a water-soluble acid solution and/or an aqueous neutral solution to a metal with a modifying component having an alkyl group or acyl group at a metal atom through an oxygen atom.